Device manufacturing-related apparatus, reticle, and device manufacturing method

ABSTRACT

A gas purge space such as a pellicle space is purged with inert gas within a short time in a projection exposure apparatus using an ultraviolet ray source such as a fluorine excimer laser as a light source. The pellicle frame of a reticle ( 20 ) with a pellicle is constituted by porous pellicle frame pieces ( 30   a,    30   b ). Inert gas is supplied into a pellicle space ( 100 ) via the porous pellicle frame piece ( 30   a ). Inert gas is exhausted together with oxygen and the like in the pellicle space ( 100 ) via the porous pellicle frame piece ( 30   b ).

FIELD OF THE INVENTION

[0001] The present invention relates to a device manufacturing-related apparatus, reticle, and device manufacturing method.

BACKGROUND OF THE INVENTION

[0002] A manufacturing process for a semiconductor element such as an LSI or VLSI formed from a micropattern uses a reduction type projection exposure apparatus for printing and forming by reduction projection a circuit pattern drawn on a mask onto a substrate coated with a photosensitive agent. With an increase in the packaging density of semiconductor elements, demands have arisen for a smaller pattern line width. The resolution has been increased for micropatterning by exposure apparatuses along with the development of a resist process.

[0003] Means for increasing the resolving power of the exposure apparatus include a method of changing the exposure wavelength to a shorter one, and a method of increasing the numerical aperture (NA) of the projection optical system.

[0004] As for the exposure wavelength, a KrF excimer laser with an oscillation wavelength of 365-nm i-line to recently 248 nm, and an ArF excimer laser with an oscillation wavelength around 193 nm have been developed. A fluorine (F₂) excimer laser with an oscillation wavelength around 157 nm is also under development.

[0005] An ArF excimer laser with a wavelength around ultraviolet rays, particularly, 193 nm, and a fluorine (F₂) excimer laser with an oscillation wavelength around 157 nm are known to have an oxygen (O₂) absorption band around their wavelength band.

[0006] For example, the 157-nm wavelength of the fluorine excimer laser falls within a wavelength region called a vacuum ultraviolet region. In this wavelength region, light is greatly absorbed by oxygen molecules, and hardly passes through the air. Light can only travel in an environment where the oxygen concentration is fully decreased. According to reference “Photochemistry of Small Molecules” (Hideo Okabe, A Wiley-Interscience Publication, 1978, p. 178), the absorption coefficient of oxygen to 157-nm light is about 190 atm⁻¹cm⁻¹. This means when 157-nm light passes through gas at an oxygen concentration of 1% at one atmospheric pressure, the transmittance per cm is only

T=exp(−190×1 cm×0.01 atm)=0.150

[0007] Oxygen absorbs light to generate ozone (O₃), and ozone promotes absorption of light, greatly decreasing the transmittance. In addition, various products generated by the photochemical reaction of the laser are deposited on the surface of an optical element, decreasing the light transmittance in the optical system.

[0008] A decrease in light quantity prolongs the time necessary for exposure and decreases the productivity.

[0009] In order to ensure sufficiently high productivity, the oxygen concentration in the optical path is suppressed to low level of several ppm order or less by a purge mechanism using inert gas such as nitrogen in the optical path of the exposure optical system of a projection exposure apparatus using a far ultraviolet laser such as an ArF excimer laser or fluorine (F₂) excimer laser as a light source.

[0010] In addition, a load-lock mechanism is arranged at a coupling portion between the inside and outside of the exposure apparatus. When a reticle or wafer is to be externally loaded into the exposure apparatus, the reticle or wafer is temporarily shielded from outside air. After the load-lock chamber is purged of the impurity with inert gas, the reticle or wafer is loaded into the exposure apparatus.

[0011]FIG. 1 is a sectional view schematically showing an example of a semiconductor exposure apparatus having a fluorine (F₂) excimer laser as a light source and a load-lock mechanism.

[0012] In FIG. 1, reference numeral 1 denotes a reticle stage for setting a reticle bearing a pattern; 2, a projection optical system for projecting the pattern on the reticle serving as a master onto a wafer serving as a photosensitive substrate; 3, a wafer stage which supports the wafer and is driven in the X, Y, Z, θ, and tilt directions; 4, an illumination optical system for illuminating the reticle with illumination light; 5, a guide optical system for guiding light from the light source to the illumination optical system 4; 6, a fluorine (F₂) excimer laser serving as a light source; 7, a masking blade for cutting off exposure light so as not to illuminate the reticle except the pattern region; 8 and 9, housings which cover the exposure optical path around the reticle stage 1 and wafer stage 3, respectively; 10, an He air-conditioner for adjusting the interiors of the projection optical system 2 and illumination optical system 4 to a predetermined He atmosphere; 11 and 12, N₂ air-conditioners for adjusting the interiors of the housings 8 and 9 to a predetermined N₂ atmosphere; 13 and 14, reticle load-lock chambers and wafer load-lock chambers used to load a reticle and wafer into the housings 8 and 9, respectively; 15 and 16, a reticle hand and wafer hand for transferring the reticle and wafer, respectively; 17, a reticle alignment mark used to adjust the reticle position; 18, a reticle stocker for stocking a plurality of reticles in the housing 8; and 19, a pre-alignment unit for pre-aligning the wafer. If necessary, the overall apparatus is stored in an environment chamber (not shown). Air controlled to a predetermined temperature is circulated within the environment chamber to keep the internal temperature of the chamber constant.

[0013] In general, a reticle is equipped with a pattern protection device called a pellicle. The pellicle prevents deposition of a foreign matter such as dust onto a reticle pattern surface, and suppresses the occurrence of defects caused by transfer of a foreign matter onto a wafer.

[0014]FIG. 2 is a schematic view showing the structure of a reticle with a pellicle. A pellicle 21 is adhered to the pattern surface of a reticle 20 with an adhesive agent or the like. The pellicle 21 is made up of a frame 22 large enough to surround the reticle pattern, and a pellicle film 23 which is adhered to one end face of the frame 22 and transmits exposure light. If a space (to be referred to as a pellicle space hereinafter) defined by the pellicle 21 and reticle 20 is completely closed, the pellicle film may expand or contract due to the difference in atmospheric pressure between the inside and outside of the pellicle space or the difference in oxygen concentration. To prevent this, a vent hole 24 is formed in the pellicle frame 22 so as to allow gas to flow between the inside and outside of the pellicle space. An auto-screen filter (not shown) is attached to the ventilation path in order to prevent an external foreign matter from entering the pellicle space via the vent hole 24.

[0015]FIG. 3 is a schematic view showing an example of a reticle transfer path in the exposure apparatus shown in FIG. 1.

[0016] In FIG. 3, reference numeral 25 denotes a foreign matter inspection device which measures the size and number of foreign matters such as dust deposited on a reticle surface or pellicle film surface. The reticle 20 is loaded manually or by a transfer device (not shown) into the reticle load-lock chamber 13 serving as the entrance of the exposure apparatus. Since the reticle and pellicle are generally adhered outside the exposure apparatus, the pellicle 21 has already been adhered to the loaded reticle 20. The interior of the reticle load-lock chamber 13 is purged with inert gas until the interior reaches an inert gas atmosphere similarly to the housing 8. After that, the reticle 20 is transferred by the reticle hand 15 to any one of the reticle stage 1, reticle stocker 18, and foreign matter inspection device 25.

[0017] As described above, an exposure apparatus using ultraviolet rays, particularly, an ArF excimer laser beam or fluorine (F₂) excimer laser beam suffers large absorption of exposure light by oxygen and moisture. To obtain a sufficient transmittance and stability of ultraviolet rays, the oxygen and moisture concentrations in the optical path are reduced and maintained. For this purpose, a load-lock mechanism is arranged at a coupling portion between the inside and outside of the exposure apparatus. When a reticle or wafer is to be externally loaded, the reticle or wafer is temporarily shielded from outside air. After the load-lock mechanism is purged of impurity with inert gas, the reticle or wafer is loaded into the exposure apparatus.

[0018] A reticle loaded into the load-lock chamber bears a pellicle, and the pellicle space can communicate with outside air only through a relatively small vent hole. This structure prolongs a time required to complete purge in the pellicle space even after the interior of the reticle load-lock chamber reaches a predetermined inert gas concentration, degrading the productivity.

[0019] To prevent this problem, Japanese Patent Laid-Open No. 9-73167 discloses an invention of adhering a reticle and pellicle in advance in an inert gas atmosphere and filling the pellicle space with inert gas at an oxygen concentration of 1% or less. However, the transmittance of 157-nm light is merely 15% per cm in atmospheric-pressure gas at an oxygen concentration of 1%. At present, the air gap between the reticle and the pellicle film is about 6 mm. Even if this space is filled with gas at an oxygen concentration of 0.1%, the transmittance of 157-nm light in the space is merely 89.2%. The total space distance of an optical path from the light source of the exposure apparatus to a wafer exceeds at least 1 m. To ensure a transmittance of 80% or more in the 1-m space, the oxygen concentration must be suppressed to 10 ppm or less in the entire optical path. The oxygen concentration is ideally 1 ppm or less. In the pellicle space, the oxygen concentration must be 1 to 100 ppm or less in terms of the balance with another space and maintenance of the transmittance in the total space distance. This also applies to the moisture and carbon dioxide gas concentrations.

[0020] The time required for inert gas purge in the pellicle space in exchanging reticles increases the standby time of the overall apparatus and influences the productivity. Purge of the pellicle space with inert gas is desirably performed within as short a time as possible. Regarding the pellicle function, dust must be prevented from entering the pellicle space during gas purge. Japanese Patent Laid-Open No. 2001-133960 proposes a method of purging the interior of the pellicle space with inert gas through gas inflow and outflow holes formed in the pellicle frame after the pellicle is adhered. However, the method disclosed in Japanese Patent Laid-Open No. 2001-133960 suffers a long purge time due to stagnation generated near the inlet hole or at the corner of the pellicle space where gas hardly flows.

SUMMARY OF THE INVENTION

[0021] The present invention has been made in consideration of the above situation, and has as its object to reduce, e.g., the nonuniformity and stagnation of the inert gas flow in a gas purge space to be purged with inert gas, and shorten the purge time in the gas purge space.

[0022] According to the first aspect of the present invention, there is provided a device manufacturing-related apparatus comprising a holding mechanism which holds a structure in which a gas purge space to be purged with inert gas is surrounded by a surrounding member, and a gas control mechanism which forms a flow of inert gas flowing into the gas purge space and flowing out from the gas purge space, to purge the gas purge space with inert gas, wherein the surrounding member has an inflow portion for allowing the gas control mechanism to supply inert gas into the gas purge space and an outflow portion for allowing the gas control mechanism to exhaust inert gas from the gas purge space, at least one of the inflow portion and the outflow portion is formed from a porous material which inert gas permeates, and the gas control mechanism forms the flow of inert gas in the gas purge space by generating between inner and outer spaces of the structure a pressure difference large enough to allow inert gas to permeate the porous material.

[0023] According to a preferred aspect of the present invention, both of the inflow portion and the outflow portion are preferably formed from the porous material which inert gas permeates.

[0024] According to another preferred aspect of the present invention, it is preferable that the surrounding member include a pellicle frame which supports a pellicle film of a reticle with a pellicle, and the inflow portion and the outflow portion be formed in the pellicle frame. In this case, the inflow portion and the outflow portion are preferably arranged at positions facing each other.

[0025] According to still another preferred aspect of the present invention, the structure preferably has a manifold outside the inflow portion, and an inner width of the manifold is preferably substantially equal to an inner width of the pellicle frame.

[0026] According to still another preferred aspect of the present invention, the structure preferably has a manifold outside the outflow portion, and an inner width of the manifold is substantially equal to an inner width of the pellicle frame.

[0027] According to still another preferred aspect of the present invention, the gas control mechanism preferably comprises a gas supply portion which supplies inert gas into the gas purge space via the inflow portion, and a gas exhaust portion which exhausts inert gas from the gas purge space via the outflow portion.

[0028] According to still another preferred aspect of the present invention, it is preferable that the gas control mechanism comprise a gas supply portion which supplies inert gas into the gas purge space via the inflow portion, and inert gas be supplied from the gas supply portion into the gas purge space via the inflow portion and directly exhausted outside the gas purge space via the outflow portion.

[0029] According to still another preferred aspect of the present invention, it is preferable that the device manufacturing-related apparatus further comprise an optical system which transmits exposure light for transferring a pattern onto a substrate, and the structure hold the optical system so as to surround the optical system.

[0030] The device manufacturing-related apparatus can be constituted as, e.g., an exposure apparatus which transfers a pattern onto a substrate, a purge apparatus which purges with inert gas an inner space of the reticle with the pellicle, a reticle stocker which stocks the reticle with the pellicle, a reticle inspection apparatus which inspects the reticle with the pellicle, or a reticle transfer box for transferring the reticle with the pellicle.

[0031] According to the second aspect of the present invention, there is provided a reticle with a pellicle, comprising a reticle, a pellicle film, and a pellicle frame which supports the pellicle film so as to form a space between the reticle and the pellicle film, wherein the pellicle frame has an inflow portion for supplying inert gas into the space and an outflow portion for exhausting inert gas from the space, and at least one of the inflow portion and the outflow portion is formed from a porous material which inert gas permeates.

[0032] According to still another aspect of the present invention, both of the inflow portion and the outflow portion are preferably formed from the porous material.

[0033] According to still another aspect of the present invention, the inflow portion and the outflow portion are preferably arranged at positions facing each other.

[0034] According to still another aspect of the present invention, the entire pellicle frame may be formed from the porous material.

[0035] According to the third aspect of the present invention, there is provided a device manufacturing method comprising manufacturing a device by using the above-described device manufacturing-related apparatus.

[0036] According to the fourth aspect of the present invention, there is provided a device manufacturing method of manufacturing a device through lithography, comprising the step of transferring a pattern onto a substrate by using the above-described device manufacturing-related apparatus which is constituted as the exposure apparatus and applied to the exposure apparatus.

[0037] Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0039]FIG. 1 is a sectional view showing the schematic arrangement of an exposure apparatus according to a preferred embodiment of the present invention;

[0040]FIG. 2 is a schematic view showing the structure of a reticle with a pellicle;

[0041]FIG. 3 is a schematic view showing an example of a reticle transfer path in the exposure apparatus shown in FIG. 1;

[0042] FIGS. 4 to 6 are views showing the schematic arrangement of a purge mechanism (gas purge apparatus) according to the first embodiment of the present invention;

[0043]FIGS. 7 and 8 are views showing the schematic arrangement of a purge mechanism (gas purge apparatus) according to the second embodiment,of the present invention;

[0044] FIGS. 9 to 11 are views showing the schematic arrangement of a purge mechanism (gas purge apparatus) according to the third embodiment of the present invention;

[0045]FIG. 12 is a view schematically showing part (light source lens system) of an exposure apparatus according to the fourth embodiment of the present invention;

[0046]FIG. 13 is a flow chart showing the flow of the whole manufacturing process of a semiconductor device; and

[0047]FIG. 14 is a flow chart showing the detailed flow of a wafer process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] An exposure apparatus according to preferred embodiments of the present invention is related to an exposure apparatus in which ultraviolet rays are used as exposure light, the interior of the exposure apparatus is purged with inert gas, and a mask pattern is projected onto a photosensitive substrate via a projection optical system. Ultraviolet rays as exposure light are preferably, e.g., far ultraviolet rays, particularly, an ArF excimer laser beam with a wavelength around 193 nm or a fluorine (F₂) excimer laser beam with a wavelength around 157 nm.

[0049] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

[0050] [First Embodiment]

[0051] FIGS. 4 to 6 are views showing the schematic arrangement of a purge mechanism (gas purge apparatus) according to the first embodiment of the present invention. This purge mechanism purges the pellicle space with inert gas. The purge mechanism can be applied to any exposure apparatus which uses a reticle with a pellicle, and can also be applied to a reticle stocker, reticle inspection apparatus, reticle transfer box, and the like. In other words, the present invention can be applied to various device manufacturing-related apparatuses which use, process, or inspect a reticle with a pellicle.

[0052] An airtight chamber 26 shown in FIGS. 4 to 6 corresponds to a housing 8 which stores a reticle stage 1 or reticle stocker 18, or a reticle load-lock chamber 13 in FIG. 1. Inert gas is introduced via an inert gas supply port 27, and exhausted via an inert gas exhaust port 28. As a result, the interior of the airtight chamber 26 is purged with inert gas.

[0053] A reticle support table 29 is arranged in a reticle transfer path in the housing 8 of FIG. 1. A reticle 20 to which a pellicle 21 is adhered is set at a predetermined position on the support table 29 manually or by a reticle hand (not shown: e.g., 15 in FIG. 3) or a transfer robot (not shown) arranged outside the airtight chamber 26. If necessary, the support table 29 may have a chucking groove for chucking and fixing a reticle.

[0054] In the first embodiment, a pellicle frame 30 is constituted by four pellicle frame pieces 30 a to 30d. The pellicle frame pieces 30 a and 30 b are made of a porous material (e.g., graphite or ceraphite), whereas the pellicle frame pieces 30 c and 30 d are made of an unporous material. In FIGS. 4 to 6, the pellicle frame piece 30 a is used as the gas supply side (gas inflow portion), and the pellicle frame piece 30 b is used as the gas exhaust side (gas outflow portion). The pellicle frame pieces 30 a and 30 b are arranged on opposite positions (sides). Manifolds 31 a and 31 b are respectively attached to the pellicle frame pieces 30 a and 30 b. The space widths (vertical widths in FIG. 6) in the manifolds 31 a and 31 b preferably almost coincide with the width (vertical width in FIG. 6) in the pellicle space 100. This can effectively reduce stagnation of the gas flow.

[0055] An inert gas supply joint 33 a is arranged near a position where the manifold 31 a is to be arranged, in order to supply inert gas into a pellicle space (space defined by the reticle 20, pellicle frame 30, and pellicle film 21) 100 serving as a gas purge space. An inert gas exhaust joint 33 b is arranged near a position where the manifold 31 b is to be arranged, in order to exhaust gas from the pellicle space 100. Driving mechanisms 34 a and 34 b move the inert gas supply and exhaust joints 33 a and 33 b closer to or apart from the manifolds 31 a and 31 b. To ensure the closeness, i.e., to prevent the inflow/outflow of gas via contact portions between the manifolds 31 a and 31 b and the inert gas supply and exhaust joints 33 a and 33 b, the manifolds 31 a and 31 b have O-rings 32 a and 32 b.

[0056]FIG. 5 is a view schematically showing a state in which inert gas is supplied into the pellicle space 100 while the driving mechanisms 34 a and 34 b bring the inert gas supply and recovery joints 33 a and 33 b into tight contact with the manifolds 31 a and 31 b.

[0057]FIG. 6 is a view when the state in FIG. 5 is viewed from below, and shows the positional relationship between the reticle 20, the pellicle frame pieces 30 a to 30 d, the gas supply joint 33 a, and the gas exhaust joint 33 b.

[0058] In FIG. 6, the porous pellicle frame pieces 30 a and 30 b are arranged on the two, right and left sides of the pellicle frame. Further, the manifolds 31 a and 31 b for pressurizing/depressurizing the pellicle space 100, the inert gas supply joint 33 a for supplying gas into the manifold 31 a, and the inert gas exhaust joint 33 b for exhausting gas from the manifold 31 b are arranged. The inert gas supply joint 33 a communicates with a path 35 a for supplying inert gas. A positive pressure regulator 36 a for adjusting the interior of the manifold 31 a to a desired positive pressure is inserted midway along the path 35 a. The inert gas exhaust joint 33 b communicates with a path 35 b for exhausting gas. A negative pressure regulator 36 b for adjusting the interior of the manifold 31 b to a desired negative pressure is inserted midway along the path 35 b.

[0059] The positive pressure regulator 36 a, path 35 a, inert gas supply joint 33 a, inert gas exhaust joint 33 b, path 35 b, and negative pressure regulator 36 b can function as a gas control mechanism which controls the flow of inert gas flowing into the pellicle space 100 and while being mixed with gas such as oxygen in the pellicle space 100, flowing from the pellicle space 100.

[0060] The process of purging the pellicle space 100 with inert gas will be explained with reference to FIGS. 4 to 6.

[0061] The reticle 20 to which the pellicle 21 is adhered is set at a predetermined position on the reticle support table 29 manually or by a reticle hand or transfer robot (not shown).

[0062] The inert gas supply and exhaust joints 33 a and 33 b are connected by the driving mechanisms 34 a and 34 b to the manifolds 31 a and 31 b adhered to the porous pellicle frame pieces 30 a and 30 b so as to press the inner sides of the O-rings 32 a and 32 b. The supply joint 33 a and exhaust joint 33 b are respectively connected to an inert gas supply apparatus and inert gas suction apparatus (neither is shown) via the supply path 35 a and exhaust path 35 b. Simultaneously when inert gas is blown into the pellicle space 100, gas in the pellicle space 100 is sucked and exhausted outside the airtight chamber 26.

[0063] Blown inert gas has passed through the porous pellicle frame piece 30 a, and thus flows from the pellicle frame piece 30 a to the facing pellicle frame piece 30 b at a uniform flow rate per unit area. Inert gas is exhausted outside the pellicle space 100 while kept uniform via the porous exhaust pellicle frame piece 30 b. While inert gas is efficiently mixed with oxygen, moisture, or other impurities present in the pellicle space without any flow stagnation, inert gas is sucked outside via the exhaust manifold 31 b formed in the exhaust-side porous pellicle frame piece 30 b, completing gas purge in the pellicle space within a short time.

[0064] Gas hardly permeates the porous material in the absence of any pressure difference between spaces on the two sides. Even if the supply and exhaust joints 33 a and 33 b are removed from the manifolds 31 a and 31 b after inert gas purge, the pellicle space 100 exhibits the same behavior as a closed space and maintains the inert gas concentration of the pellicle space 100 during a short time until the reticle 20 with the pellicle is transferred to the stage. The porous material as the pellicle frame pieces 30 a and 30 b serves as a filter, and can prevent the inflow of dust into the pellicle space 100. Note that a particle prevention or chemical contamination prevention filter may be inserted midway along the path for supplying gas to the pellicle frame piece 30 a.

[0065] The inert gas supply and exhaust joints 33 a and 33 b as shown in FIGS. 4 to 6 can also be arranged in the reticle stocker 18 (see FIG. 1). In this case, inert gas purge in the pellicle space is not executed in the reticle load-lock chamber 13 for a reticle which is externally loaded into the exposure apparatus, and is not used for exposure at once but is temporarily stocked in the reticle stocker 18. Instead, the reticle is loaded into a predetermined slot of the reticle stocker 18 where the joint is arranged, and then inert gas purge in the pellicle space can be executed in the stocker. Accordingly, a satisfactory purge time can be ensured to decrease the inert gas concentration in the pellicle space to a low level in advance. In addition, the inert gas purge time in the reticle load-lock chamber 13 can be further shortened or omitted.

[0066] The location where the purge mechanism including the inert gas supply and exhaust joints is arranged is not limited to the reticle stage, reticle stocker, or reticle load-lock chamber. The purge mechanism can be arranged at various locations, e.g., inside a pellicle inspection apparatus or in a reticle transfer path within a closed chamber. When the purge mechanism is arranged midway along the transfer path, the reticle need not be transferred to a purge mechanism outside the transfer path, shortening the transfer time in the whole exposure apparatus and increasing the productivity. The purge mechanism location is not limited to one, but purge mechanisms can be arranged at a plurality of portions, and automatically select and execute inert gas purge at an optimal location suitable for a reticle use plan.

[0067] [Second Embodiment]

[0068]FIGS. 7 and 8 are views showing the schematic arrangement of a purge mechanism (gas purge apparatus) according to the second embodiment of the present invention. FIG. 7 is a schematic sectional view when the purge mechanism is viewed from the lateral direction. FIG. 8 is a view when the purge mechanism in FIG. 7 is viewed from below. This purge mechanism purges the pellicle space with inert gas. The purge mechanism can be applied to any exposure apparatus which uses a reticle with a pellicle, and can also be applied to a reticle stocker, reticle inspection apparatus, reticle transfer box, and the like. That is, the present invention can be applied to various device manufacturing-related apparatuses which use, process, or inspect a reticle with a pellicle. The same reference numerals as in the first embodiment denote the same parts. The first embodiment applies to matters which will not be mentioned in the second embodiment.

[0069] In the first embodiment, portions (two sides out of four sides) of the pellicle frame are made of a porous material. The spaces in manifolds connected to the pellicle frame portions are pressurized/depressurized, supplying inert gas into the pellicle space and exhausting gas from the pellicle space. In the second embodiment, the entire pellicle frame is made of a porous material. While the inert gas supply side (inflow side) is pressurized, the outflow side is not depressurized. More specifically, in the second embodiment, inert gas is supplied into the pellicle space via a very small portion (inflow portion) of the pellicle frame, and exhausted from the pellicle space via the remaining portion (outflow portion) of the pellicle frame.

[0070] The second embodiment will be described in more detail with reference to FIGS. 7 and 8. In the second embodiment, a driving mechanism 34 a connects an inert gas supply joint 33 a via an O-ring 32 a to a manifold 31 a arranged at a portion (inflow portion) of a pellicle frame 30. After the inert gas supply joint 33 a is connected, pressurized inert gas is supplied into a pellicle space 100 via the inert gas supply joint 33 a. As shown in FIG. 8, the inert gas supply manifold 31 a is adhered to a very small portion (inflow portion) of the pellicle frame 30. When the interior of the manifold 31 a is pressurized by inert gas, only this portion of the pellicle frame 30 functions as an inert gas inflow portion 30 e, and the remaining portion of the pellicle frame functions as an inert gas outflow portion 30 f.

[0071] Inert gas having passed through the inflow portion 30 e of the pellicle frame 30 radially flows toward the outflow portion 30 f of the pellicle frame 30. Inert gas flows out from the outflow portion 30 f to the pellicle frame at a predetermined flow rate per area because of the nature of the porous material. Outflow gas is exhausted outside an airtight chamber 26 together with other gases in the airtight chamber 26 via an inert gas exhaust line 28.

[0072] To make gas permeate the porous material, the pressure difference must be given to a certain degree on the two sides of the porous material because of a high pipe resistance of the porous material. In the second embodiment, the outside of the gas exhaust porous material 30 f is at the atmospheric pressure. Gas does not permeate the porous material unless the internal pressure of the pellicle space 100 is set higher than the atmospheric pressure by the pressure difference or more. To the contrary, the pressure resistance of a pellicle film 21 is low. Considering this, the second embodiment increases the area of the porous material which constitutes the outflow portion 30 f, thereby supplying nitrogen into the pellicle space with a small pressure difference.

[0073] In the first embodiment, gas is forcibly exhausted from the pellicle space by setting a negative pressure outside the pellicle space. In the second embodiment, compared to the first embodiment, the flow rate of inert gas which can be supplied into the pellicle space and exhausted from it is low. In the second embodiment, the gas purge time is longer than that in the first embodiment because the distance from the inflow portion 30 e (corresponding to the pellicle frame piece 30 a in the first embodiment) for supplying inert gas into the pellicle frame to the outflow portion 30 f (corresponding to the pellicle frame piece 30 b in the first embodiment) for exhausting gas from the pellicle space is not the same between all portions, unlike the first embodiment. However, according to the second embodiment, any outflow-side manifold can be eliminated, and the pellicle frame itself can be made of a single material. The second embodiment is, therefore, superior to the first embodiment in that the outflow-side gas exhaust mechanism can be eliminated to simplify the purge mechanism and reduce the purge mechanism manufacturing cost. Further, the second embodiment is superior to the first embodiment in that the structure of a reticle with a pellicle is simple and can be easily formed and thus the manufacturing cost of the reticle with the pellicle can be reduced.

[0074] The disadvantage of the second embodiment results from forming the whole pellicle frame from a porous material and keeping the gas outflow side at the atmospheric pressure. To prevent this, the gas outflow side may be adjusted to a negative pressure to increase the gas inflow/outflow amount in the second embodiment, similar to the first embodiment. It is also possible to seal, with a sealing material, porous material portions on the two, upper and lower sides of the pellicle frame shown in FIG. 8, arrange a gas outflow manifold 31 b on one left side, similar to the first embodiment, adjust the interior of the manifold 31 b to a negative pressure, and exhaust gas.

[0075] [Third Embodiment]

[0076] FIGS. 9 to 11 are views showing the schematic arrangement of a purge mechanism (gas purge apparatus) according to the third embodiment of the present invention. More specifically, FIG. 9 is a schematic view when the purge mechanism is viewed from the lateral direction. FIG. 10 is a view showing a state in which inert gas is supplied into the pellicle space by the purge mechanism shown in FIG. 9. FIG. 11 is a view when the purge mechanism in FIG. 10 is viewed from below. The same reference numerals as in the first embodiment denote the same parts. The first embodiment applies to matters which will not be mentioned in the third embodiment.

[0077] In the third embodiment, porous members 30 a and 30 b are arranged outside a pellicle frame 22 having vent holes 24, and manifolds 31 a and 31 b are arranged outside the porous members 30 a and 30 b. More specifically, in the third embodiment, the vent holes 24 are formed on two facing sides of the pellicle frame 22 made of an unporous material. The porous members 30 a and 30 b are arranged outside these two sides, and the manifolds 31 a and 31 b are arranged outside the two porous members 30 a and 30 b.

[0078] The process of purging a pellicle space 100 with inert gas will be explained with reference to FIGS. 9 to 11.

[0079] A reticle 20 to which a pellicle 21 is adhered is set at a predetermined position on a reticle support table 29 manually or by a reticle hand or transfer robot (not shown).

[0080] Inert gas supply and exhaust joints 33 a and 33 b are connected by driving mechanisms 34 a and 34 b via O-rings 32 a and 32 b to the manifolds 31 a and 31 b adhered to the porous members 30 a and 30 b. The supply joint 33 a and exhaust joint 33 b are respectively connected to an inert gas supply apparatus and inert gas suction apparatus (neither is shown) via a supply path 35 a and exhaust path 35 b. Simultaneously when inert gas is blown into the pellicle space 100, gas in the pellicle space 100 is sucked and exhausted outside the airtight chamber 26.

[0081] Gas hardly permeates the porous material in the absence of any pressure difference between spaces on the two sides. Even if the supply and exhaust joints 33 a and 33 b are removed from the manifolds 31 a and 31 b after inert gas purge, the pellicle space 100 exhibits the same behavior as a closed space and maintains the gas concentration of the pellicle space 100 during a short time until the reticle 20 with the pellicle is transferred to the stage. The porous members 30 a and 30 b serve as a filter, and can prevent the inflow of dust into the pellicle space 100. Note that a particle prevention or chemical contamination prevention filter may be inserted midway along the path for supplying gas to the porous member 30 a.

[0082] The third embodiment can fabricate a reticle with a pellicle by, e.g., adhering porous members to the outer surface of the four-side pellicle frame having vent holes. The reticle with the pellicle can be manufactured more easily than the first embodiment in which porous and unporous materials are coupled to constitute a four-side pellicle frame. That is, the third embodiment simplifies the pellicle frame fabrication process.

[0083] [Fourth Embodiment]

[0084] An application of the purge mechanism according to the present invention to the light source lens system of an exposure apparatus will be described as the fourth embodiment of the present invention. FIG. 12 is a view schematically showing part (light source lens system) of the exposure apparatus according to the fourth embodiment of the present invention. The same reference numerals as in the first embodiment denote the same parts. The first embodiment applies to matters which will not be mentioned in the fourth embodiment.

[0085] The light source lens system is constituted by optical elements such as many lenses 37 a and 37 b and a mirror 38. The light source lens system illuminates an illumination region on a reticle with a laser beam from the light source at a uniform illuminance. These optical components are incorporated in a housing 39. The interior of the housing 39 is purged with high-concentration inert gas via an inert gas supply line 27 and inert gas exhaust line 28. When the housing 39 is open for maintenance or the like, outside air flows into the housing 39. To operate the exposure apparatus again, the interior of the housing 39 must be purged of outside air with inert gas. When the housing 39 incorporates optical components, spaces between the lenses 37 a to 37 c held in a lens holding structure 40 held at a predetermined position by a holding mechanism 42 in the housing 39 are half-sealed. Inert gas hardly flows to this portion, and gas purge is not performed.

[0086] To prevent this, a purge mechanism which supplies inert gas into a purge space via a porous material is assembled into the lens holding structure 40 in the fourth embodiment, similar to the first to third embodiments.

[0087] More specifically, in the fourth embodiment, as shown in FIG. 12, a porous member 30 a for supplying inert gas is arranged on the wall (e.g., inner wall) of the lens holding structure 40. Part of the lens holding structure 40 is processed into a manifold shape. Pressurized gas is supplied through an inert gas supply path 35 a, and inert gas is supplied to the inter-lens space via the porous member 30 a. Inert gas supplied into the inter-lens space has passed through the porous member 30 a, and thus flows toward a facing surface (left side in FIG. 12) with high uniformity in the plane direction of the porous member 30 a. Gas in the inter-lens space is exhausted outside the lens holding structure 40 via exhaust holes 41 formed in the facing surface. While inert gas is efficiently mixed with oxygen, moisture, or other impurities present in the inter-lens space without any stagnation, inert gas can be exhausted outside via the exhaust holes 41, completing gas purge in the inter-lens space within a short time.

[0088] Even if the inert gas concentration in the purge space (inter-lens space) decreases owing to maintenance or the like, the standby time of the exposure apparatus until the inert gas concentration increases can be shortened. The fourth embodiment has exemplified the light source lens system. The method of supplying inert gas using a porous material is not limited to the light source lens system, and can be applied to purge of a purge space in all optical components such as a projection lens system and measurement lens system, and other mechanisms.

[0089] [Device Manufacturing Method]

[0090] A semiconductor device manufacturing process using the above-described exposure apparatus will be explained. FIG. 13 is a flow chart showing the flow of the whole manufacturing process of a semiconductor device. In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask formation), a mask is formed based on the designed circuit pattern. In step 3 (wafer formation), a wafer is formed using a material such as silicon. In step 4 (wafer process) called a pre-process, an actual circuit is formed on the wafer by lithography using the mask and wafer. Step 5 (assembly) called a post-process is the step of forming a semiconductor chip by using the wafer formed in step 4, and includes an assembly process (dicing and bonding) and packaging process (chip encapsulation). In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and durability test. After these steps, the semiconductor device is completed and shipped (step 7).

[0091]FIG. 14 is a flow chart showing the detailed flow of the wafer process. In step 11 (oxidation), the wafer surface is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted in the wafer. In step 15 (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the above-described exposure apparatus transfers a circuit pattern onto the wafer. In step 17 (developing), the exposed wafer is developed. In step 18 (etching), the resist is etched except the developed resist image. In step 19 (resist removal), an unnecessary resist after etching is removed. These steps are repeated to form multiple circuit patterns on the wafer.

[0092] As described above, according to preferred embodiments of the present invention, inert gas purge in the pellicle space of a reticle with a pellicle loaded into the apparatus can be efficiently performed within a short time in a projection exposure apparatus using an ultraviolet ray source such as a fluorine excimer laser as a light source.

[0093] Even when the closed inert gas purge space is broken for maintenance or adjustment, the purge space can be returned to a necessary purge level within a short time, shortening the standby time of the apparatus.

[0094] This realizes high-precision, stable exposure amount control without decreasing the productivity of the exposure apparatus, and a fine circuit pattern can be efficiently, stably projected onto a substrate.

[0095] The present invention can reduce, e.g., the nonuniformity and stagnation of the inert gas flow in a gas purge space to be purged with inert gas, and shorten the purge time in the gas purge space.

[0096] As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the claims. 

What is claimed is:
 1. A device manufacturing-related apparatus comprising: a holding mechanism which holds a structure in which a gas purge space to be purged with inert gas is surrounded by a surrounding member; and a gas control mechanism which forms a flow of inert gas flowing into the gas purge space and flowing out from the gas purge space, to purge the gas purge space with inert gas, wherein the surrounding member has an inflow portion for allowing said gas control mechanism to supply inert gas into the gas purge space and an outflow portion for allowing said gas control mechanism to exhaust inert gas from the gas purge space, at least one of the inflow portion and the outflow portion is formed from a porous material which inert gas permeates, and said gas control mechanism forms the flow of inert gas in the gas purge space by generating between inner and outer spaces of the structure a pressure difference large enough to allow inert gas to permeate the porous material.
 2. The apparatus according to claim 1, wherein both of the inflow portion and the outflow portion are formed from the porous material which inert gas permeates.
 3. The apparatus according to claim 1, wherein the surrounding member includes a pellicle frame which supports a pellicle film of a reticle with a pellicle, and the inflow portion and the outflow portion are formed in the pellicle frame.
 4. The apparatus according to claim 3, wherein the inflow portion and the outflow portion are arranged at positions facing each other.
 5. The apparatus according to claim 3, wherein the structure has a manifold outside the inflow portion.
 6. The apparatus according to claim 5, wherein an inner width of the manifold is substantially equal to an inner width of the pellicle frame.
 7. The apparatus according to claim 3, wherein the structure has a manifold outside the outflow portion.
 8. The apparatus according to claim 7, wherein an inner width of the manifold is substantially equal to an inner width of the pellicle frame.
 9. The apparatus according to claim 3, wherein the structure has manifolds outside the inflow portion and the outflow portion.
 10. The apparatus according to claim 9, wherein an inner width of each manifold is substantially equal to an inner width of the pellicle frame.
 11. The apparatus according to claim 1, wherein said gas control mechanism comprises a gas supply portion which supplies inert gas into the gas purge space via the inflow portion, and a gas exhaust portion which exhausts inert gas from the gas purge space via the outflow portion.
 12. The apparatus according to claim 1, wherein said gas control mechanism comprises a gas supply portion which supplies inert gas into the gas purge space via the inflow portion, and inert gas is supplied from the gas supply portion into the gas purge space via the inflow portion and directly exhausted outside the gas purge space via the outflow portion.
 13. The apparatus according to claim 1, wherein the device manufacturing-related apparatus further comprises an optical system which transmits exposure light for transferring a pattern onto a substrate, and the structure holds said optical system so as to surround said optical system.
 14. The apparatus according to claim 1, wherein the device manufacturing-related apparatus is constituted as an exposure apparatus which transfers a pattern onto a substrate.
 15. The apparatus according to claim 4, wherein the device manufacturing-related apparatus is constituted as a purge apparatus which purges with inert gas an inner space of the reticle with the pellicle.
 16. The apparatus according to claim 4, wherein the device manufacturing-related apparatus is constituted as a reticle stocker which stocks the reticle with the pellicle.
 17. The apparatus according to claim 4, wherein the device manufacturing-related apparatus is constituted as a reticle inspection apparatus which inspects the reticle with the pellicle.
 18. The apparatus according to claim 4, wherein the device manufacturing-related apparatus is constituted as a reticle transfer box for transferring the reticle with the pellicle.
 19. A reticle with a pellicle, comprising: a reticle; a pellicle film; and a pellicle frame which supports said pellicle film so as to form a space between said reticle and said pellicle film, wherein said pellicle frame has an inflow portion for supplying inert gas into the space and an outflow portion for exhausting inert gas from the space, and at least one of the inflow portion and the outflow portion is formed from a porous material which inert gas permeates.
 20. The reticle according to claim 19, wherein both of the inflow portion and the outflow portion are formed from the porous material.
 21. The reticle according to claim 19, wherein the inflow portion and the outflow portion are arranged at positions facing each other.
 22. The reticle according to claim 19, wherein the entire pellicle frame is formed from the porous material.
 23. A device manufacturing method comprising the step of manufacturing a device by using a device manufacturing-related apparatus defined in claim
 1. 24. A device manufacturing method of manufacturing a device through lithography, comprising the step of transferring a pattern onto a substrate by using a device manufacturing-related apparatus defined in claim 14 which is constituted as the exposure apparatus. 